Manufacture of seamless tubes



June 9,.1931..

w. KUNST I MANUFACTURE OF SEAMLESS TUBES Filed April 4. 1927 Patented-June 9, 1931 UNITED STATES PATENT OFFICE WILHELM KUNS'I, F BARMEN,GERMANY, ASSIGN'OR T0 HEINRICH ESSEROF HILDEN, GERMANY."

SEAMLESS TUBES Application filed April 4, 1927, Serial No. 181,010, andin Germany January 17, 1927.

i My invention relates to the manufacture of seamless tubes by rollingand has for its object to simplify and expedite the production.

It has already been proposed to produce seamless tubes from a tubularblank by roll ing it out upon a roughing and a coggin mill and finishingrolls, a reducing mill eing provided between the cogging andthe'finishing trains in which the billet or ingot coming from thecogging mill is reduced in diameter.- In this way a large number ofpasses can be saved in the finishing rolls.

The present invention differs fundamentally from the foregoing in thatthe thick walled tubular blank is reduced to a thinner Wall in apiercing mill, the ingot bein then reduced to the desired diameter in are ucing rolling mill, and then rolled out to the final wall-thicknessin a two-high rolling mill.

In the drawings aflixed to this specification and forming part thereof,the invention is illustrated diagrammatically by Way of example. i

In the drawings Fig. 1 shows a piercing mill 1, and mandrel 2 in thecourse of reducing the Wall thick- 'ness of a thickwalled tubular blank3,

- Fig. 2 illustrating a reducing rolling mill 4 and the tubularworkpiece 5 whose outer dianiieter is reduced to the extent finallydesire Fig. 3 shows a two high mill 6 and the workpiece 7 in the courseof having its wall thickness further reduced, the workpiece being at thesame time stretched to assume its final length Without its outerdiameter being changed.

Obviously a blank of predetermined great wall-thickness can thus beconverted into a tube of any inferior wall-thickness by adding orremoving the respective passes and mandrels. v

In this way not only is the process of production shortened andsimplified, but the construction of the whole plant for carrying it outis also simplified. In the place of the roughingjand cogging millsapiercing mill is employed, whereby a whole rolling set is saved.Reheating of the blank before the by rolling, comprising reducing thewall thickness of a comparatively thick-Walled tubular blank, thereafterreducing the diam eter of the said blankto the final diameter 5 andthereafter reducing the wall thickness of saidblank to thefinal'thickness.

2. The process of producing seamless tubes by rolling, comprisingreducing the wall thickness of a comparatively thick-walled'tubularblank in a piercing mill, thereafter reducing the diameter ofthe said blank to the final diameter in a reducing mill and thereafterreducing the wall-thickness of said blank to the final thickness in atwohigh rolling mill.

In testimony whereof I afiix my signature.

WILHELM KUNST.

